The battle for Allied Stores escalated.

The retailer, which has agreed to be acquired by the nation’s biggest mall developer for $3.55 billion in cash, said its board of directors had adopted a “poison pill” to discourage the efforts of persistent and hostile suitor Campeau Corp. Allied obtained a federal court order temporarily blocking Campeau’s latest offer until a court hearing Oct. 20 in U.S. District Court in Manhattan. Earlier in the day, Campeau had said it would proceed with its $66-a-share cash tender offer for control of Allied in a deal that would be worth $3.5 billion if completed.